Washington, DC—More than 15% of children and adolescents in the United States are obese, but how their weight affects medication dosage remains a guessing game in most cases.

That’s according to a study conducted at Children’s National Health System with the FDA Center for Drug Evaluation and Research. Researchers surveyed pediatric medical and clinical pharmacology reviews under the FDA Amendments Act of 2007 and the FDA Safety and Innovation Act of 2012 (FDASIA).

Using search terms related to weight and size, they found that none of the 89 product labels reviewed provided dosing information related to obesity. The results were published online recently by The Journal of Clinical Pharmacology.

The problem, according to study authors, is that obesity increases the percentage of fat tissue compared to the percentage of lean body mass and also enlarges kidney size. Those are issues that affect how the body takes up medicine, where it retains it, and how quickly it is excreted, the report notes.

“We are making progress in expanding the number of medicines with pediatric labeling, but we need to do more concerning providing dosing guidelines for children with obesity,” explained lead author Janelle D. Vaughns, MD, director of bariatric anesthesia at Children’s National. “Moving forward, regulators, clinicians and the pharmaceutical industry should consider enrolling more obese patients in pediatric clinical trials to facilitate the safe and effective use of the next generation of medicines by obese children and adolescents.”

The researchers note that 45 drugs studied in pediatric patients under the FDA Amendments Act were found to have statements and key words in the medical and clinical pharmacology reviews and labels related to obesity, while 44 products were identified similarly with pediatric studies under FDASIA.

Yet, of the 89 product labels identified, none provided dosing information related to obesity, the review noted, while the effect of body mass index on drug pharmacokinetics was mentioned in only four labels.

“We conclude that there is little information presently available to provide guidance related to dosing in obese pediatric patients,” the study authors write.